Electron discharge device



Dec. 24, 1946. Q 7 L, P. SMITH 2,413,251

ELECTRON DISCHARGE DEVICE Filed Nov. 26, 1942 2 Sheets-Sheet 1 INVENTOR LLogD PfmrrH ATTORNEY Dec. 24, 1946. L. P. SMITH 2,413,251

ELECTRON DISCHARGE DEVICE Filed Nov. 26, 1942 2 Sheets-Shet 2 I, I' l IN'VENTOR LLogD /THTH ATTORNEY Patented Dec. 24, 1946 ZAIZLZ'SI ELECTRON DISCHARGE DEVICE Lloyd P. Smith, Princeton, N. 3., assignor to Radio Corporation of America, a corporation of Delaware Application November 26, 1942, Serial No. 466,993

Claims.

My invention relates to electron discharge devices, particularly such devices useful as oscillators at ultra high frequencies and utilizing resonators or resonant cavities.

In one form of an electron discharge device utilizing a resonator, a beam of electrons is directed toward a, collectorand passes through a resonator comprising a hollow conducting member and provided with a passageway through which the beam is directed. A gap in the passageway surrounds the discharge path and lies in a plane transverse to the direction or" the path of the beam of electrons. The hollow conducting member during operation is energized so that an electric field is set up and confined within the member, the high frequency oscillating field appearing across the gap. An interchange of energy takes place between the field across the gap and the beam of electrons passing through the resonator.

In some oscillators using resonators, electrons are allowed to pass through the opening in the resonator in which the high frequency field is confied in such a way that at repeated intervals motion of the electrons is retarded and part of the energy is transferred to the high frequency field. It is usually not possible to convert all the kinetic energy of the electrons into field energ in one transit, especially when the loading on the resonator which forms the output circuit is variable. This could be overcome by causing electrons to oscillate back and forth through the resonator until nearly all of their kinetic energy is transferred to the electromagnetic field provided th period of oscillation of the electrons can be made independentofhow much energy they have lost, This is necessary to insure that an electron which loses energy on the first transit of the cavity loses energy on all subsequent transits.

An object of my invention is to provide an electron discharge device of improved design, particularly useful as an oscillator at ultra high frequencies.

Another object of my invention is to provide such a device utilizing resonators in which energy is successively extracted from electrons which are made to oscillate a plurality of times through the resonator.

A still further object of, my invention is to provide such a device in which the electrons will oscillate back and forth through the electromagnetic field of the resonator with a period of oscillation independent of the energy lost by the electrons.

More specifically it is an object of my invention to provide an electron discharge device having an electrode structure which will cause electrons to oscillate back and forth through the electrode structure with a period of oscillation independent of the energy lost by the electrons.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims,'1but the invention itself will best be understood by reference to the following description taken .in connection with the accompanying drawings in which Figure 1 is a diagram of the transverse sections of the electrode structures necessary to practice my invention, Figure 2 is a'voltage gradient diagram produced by electrode structures of the kind shown in Figure 1, Figure 3 is a transverse section of an electron discharge device made according to my invention and taken along the line 3-3 of Figure 4., which shows the longitudinal section of the device shown in Figure 3, Figure 5 is a transverse section of a modification of an electron discharge device made according to my 'invention and Figure 6 is a circuit diagram of an electron discharge device made according to my invention.

Below is described a unique system of electrodes of an electron discharge device and between which an electron will oscillate with a period which is independent of its energy. The electrode system is described in combination with a resonant cavity or resonator to form a high frequency oscillator. An electron will move back and forth along a line with a period which is independent of its energy or amplitude only provided the force tending to return it to its equilibrium point is proportional to the distance away from this point. This requires the potential gradient to follow the form V=Vo:r In a two dimensional potential field there is only one system of electrodes which accomplishes this. It can be shown that these are the family of hyperbolic cylinders shown in section in Figure 1. This family of hyperbolae satisfies the equation V 0 (x y constant.

V0 is the potential difference between the point 0 and a point one centimeteraway from B on the line 3C. V is the potential at any distance X from I] measured along 60 or 60'. If the frequency of the oscillating electron is i then V0 (volts) :1.12 X 10- f Assume electrodes having the form. and shape shown in Figure 1, to be assembled such that they lie along the asymptotes AA and BB and along the hyperbolas C and C. If an opening is made in the electrodes at the intersection of the asymptotes AA, BB which asymptotes intersect at right angles, and a potential is applied to these electrodes which is positive relatively to the potential applied to the electrodes lying on the. hyperbolae C and C, then an electron starting anywhere from rest on line CC will oscillate back and forth on this line with a period which -on the opposite side of the resonator.

3 is fixed by the applied potential and distance C=0C, but it is the same no matter from what position the electron was started. This is entirely equivalent to the period being the same for electrons with difierent maximum kinetic energies.

The diagram in Figure 2 represents the voltage gradient of the electric field existing between the point 0 and the surfaces of the electrodes at points CC. This curve satisfies the equation V=--Vo$ The cross-hatched region in Figure 1 is available for the resonant cavity or resonator so that a complete oscillator may be constructed. The structure may be made long in a direction at right angles to the plane of the paper. The cathodes are linear and at the same potential as and really form a part of the hyperbolic electrode C and C. The cavity walls become the anode.

An electron discharge device made according to my invention and satisfying the above requirements is shown in Figures 3 and 4. The resonator 9 is provided with walls H), II, l2 and iii which walls form the anode electrodes which lie along asymptotes corresponding to asymptotes AA and BB in Figure 1. Apertures I5 and I5 are provided at the intersection to permit the passage of electrons through the resonator, the electrodes being spaced so as to provide a gap l4 across which, during operation, a radio frequency field is generated and with which electrons react to transfer energy between the electrons and the radio frequency field within the resonator. As shown in Figure 4 the two resonant cavities having sector shaped transverse sections communicate with each other through closed chambers 3| and 32 at each end of the device. It is possible to eliminate the top and bottom chambers 3| and 32, and the device will function. However, the chambers 3| and 32 couple the fields in the sector shaped sections and insure that both sections will operate in proper phase.

An electrode whose surface is defined by a hyperbola includes segments I7 and i8 which find their duplicates in the segments l9 and Electrons are furnished by means of an indirectly heated cathode 2| and if desired a like cathode 22 may be placed on the other side, although this is not essential. The electrode segments l! and I8 are electrically strapped together by the conductor l1 and the electrode segments l9 and 20 are electrically strapped together by means of conductor it to form a single electrode provided with a slot in which the cathodes lie.

In order to provide a cathode assembly, oppositely disposed insulating members, preferably mica spacers 23 and 24, are secured to the upper and lower ends of the electrode segments I! and I8 and I9 and 20 by, for example, tabs 25 and 26. These spacers frictionally support the cathodes 2| and 22 in position. The assemblies are supported from the walls In and II and I2 and I3 by means of glass bead support arrangements such as 29 and 30.

In order to provide an enclosure which may be evacuated, a closure member 33 is sealed to the lip 34 supported by the anode electrode m, l and the top and bottom chambers 3| and 32. The cathode lead 35 may be extended through an insulatng bead in the lip or flange 34 and likewise the cathode heaters 35 may be extended through the lip 34. In order to apply a biasing voltage if desired to the hyperbolic electrodes, leads 31 and 3'! may be provided.

The former will not reach the opposite electrodes I9, 26 but will stop and return and again pass through the cavity, giving up still more energy. This is repeated and these electrons finally reach the anode or cavity walls. Electrons which gain energy on their first passage through the cavity strike the electrodes I9, 20 and 2| and are thereby removed from the beam so that they remove no further energy from the radio frequency field. This provides the mechanism by which the appropriate electron phasing is accomplished. To increase the cathode area as Well as the symmetry of the arrangement a second cathode may be employed as shown at 22. Electrons from cathode 22 are automatically synchronized by the high frequency field within the resonator.

When electrons depart from the plane passing through the cathodes they will experience a force to the side of the plane and be collected by the sides of the resonator which function as collectors or anodes. In order to keep the electrons near the plane passing through the cathodes a magnetic field may be established in the direction of the plane by means of magnet 39. The magnitude of the magnetic field is not critical and needs only to be suflicient to hold the electrons near the plane mentioned.

In some cases it may be desirable to operate the apparatus as an oscillator intermittently, in which case a partial grid may be substituted for a slot part of the electrodes |8 by running grid wires across said slot as at 33 in Figure 5. A cathode 2| is mounted slightly behind these electrodes as shown in Figure 5. Electrons will not pass through the grid when a potential is applied to the cathode, which is positive with respect to the grid or hyperbolic electrodes.

In the arrangement shown in Figure 5, in which like numerals indicate parts corresponding to like parts in Figure l, a cathode 2| is placed behind the hyperbolic electrodes I8 and is shielded by the shielding member 40. A voltage may be applied between hyperbolic electrodes and I8 and the cathode for modulating or determining the period during which electrons may flow from the cathode into the electrode system comprising the hyperbolic electrodes and the resonator.

A circuit diagram of my invention is shown in Figure 6. The indirectly heated cathode 2| is heated by means of the heating transformer 4|. Biasing voltage between the cathode and the hyperbolic electrodes is indicated at 43. Means for controlling the electron flow is indicated at 44. A positive voltage source for applying a positive voltage between the resonator and anode electrodes and the hyperbolic electrodes is lndicated at 42.

In an apparatus of the kind described and utilizing my invention, high efficiency, which is more or less independent of the load applied to the cavity results. The magnetic field is not critical, and intermittent operation with low control voltage and a high Q radio frequency circuit is made possible.

While I have indicated the preferred embodiments of my invention of which I am now aware and have also indicated only one specific application for which my invention may be employed, it will be apparent that my invention is by no means limited to the exact forms illustrated or the use indicated, but that many variations may be made in the particular structure used and the purpose for which it is employed without departing from the scope of my invention as set forth in the appended claims.

What I claim as new is:

1. An electron discharge device including an electrode having surfaces approaching each other at an angle of 90 and having an aperture at the intersection of said surfaces, and a second electrode having a hyperbolic surface and positioned between and spaced from said intersecting surfaces the extensions of which provide the asymptotes for the extended surfaces of said second electrode, and meansregistering with said apertures for directing a stream of electrons through said aperture and between said electrodes and along a line lying in a plane bisecting the angle between said intersecting surfaces and passing through the axis of the hyperbole. defining the surface of the second electrode.

2. An electron discharge device having an electrode provided with surfaces intersecting each other and having an aperture at said intersection, a second electrode spaced from said first electrode and having a surface the transverse section of which is defined by a hyperbola, the intersecting surfaces of said first electrode forming the asymptotes for said hyperbola, said second electrode having an aperture registering with the aperture in said first electrode, andmeans registering with said apertures for directing a stream of electrons between said apertures.

3. An electron discharge device having an electrode provided with surfaces intersecting each other and having an aperture at said inter-- section, a second electrode spaced from said first electrode and having a surface, the transverse section of which is defined by a hyperbola, the intersecting surfaces extended of said first electrode forming the asymptotes for said hyperbola, and means registering with said apertures for supplying a stream of electrons directed along a path from the surface of said second electrode through said aperture.

4. An electron discharge device having an electrode provided with surfaces intersecting each other and having an aperture at said intersection, a second electrode spaced from said first electrode and having a surface the transverse section of which is defined by a hyperbola, the intersecting surfaces of said first electrode forming the asymptotes for said hyperbola, said second electrode having an aperture registering with the aperture in said first electrode, and means registering with said apertures for directing a stream of electrons from an aperture in one electrode through the aperture in the other electrode, and an electrode in the path of the electrons passing through said last aperture.

5 An electron discharge device having an electrode provided with surfaces intersecting each other at 90 and having an aperture at the intersection, a second electrode spaced from said first electrode and having a surface the transverse section of which is defined by a hyperbola, the intersecting surfaces of said first electrode forming the asymptotes for said hyperbola, said second electrode having an aperture registering with the aperture in saidfirst electrode, and means registering with said aperture for directing a stream of electrons from an aperture in one electrode through the aperture in the other electrode.

6. An electron discharge device having a first electrode provided with surfaces intersecting each other and having an aperture at said intersection, a second electrode spaced from said first electrode and having a surface the transverse section of which is defined by a hyperbola, the intersecting surfaces extended of said first electrode forming the asymptotes for said hyperbola, a source of electrons lying in the surface of said second electrode and registering with the aperture in said first electrode, said first electrode having an independent lead adapted to be at a potential positive with respect to said second electrode during operation of said device to cause electrons to pass from said source of electrons through said aperture.

7. An electron discharge device having a first electrode provided with surfaces intersecting each other and having an aperture at the intersection, and a second electrode spaced from said first electrode and having a, surface the transverse section of which is defined by a hyperbola, the intersecting surfaces extended of said first electrode forming the asymptotes for said hyperbola, a third electrode provided with surfaces intersecting each other and lying parallel to the surfaces of the first electrode and having an aperture registering with the aperture in said first electrode, and a fourth electrode having a surface lying in a hyperbola, the intersecting surfaces extended of said third electrode forming the asymptotes for said last hyperbola, and means registering with said apertures for supplying a stream of electrons passing through said apertures and between the first and fourth electrodes.

8. An electron discharge device having a first electrode provided with surfaces intersecting each other and having an aperture at the intersection, and a second electrode spaced from said first electrode and having a surface, the transverse section of which is defined by a hyperbola, the intersecting surfaces extended of said first electrode forming the asymptotes for said hyperbola, the second electrode having an aperture registering with the aperture in said first electrode, a third electrode provided with surfaces intersecting each other and lying parallel to the surfaces of said first electrode and having an aperture registering with the aperture in said first elec trode, and a fourth electrode having a surface defined by a hyperbola, the intersecting surfacesextended of said third electrode forming the asymptotes for said last hyperbola, and means registering with said apertures for supplying a stream of electrons passing through said apertures and between the first and fourth electrodes.

9. An electron discharge device having a first electrode provided with surfaces intersecting each other and having an aperture at the intersection, and a second electrode spaced from said first electrode and having a surface, the transverse section of which is defined by a hyperbola, the intersecting surfaces extended of said first electrode forming the asymptotes for said hyperbola, the second electrode having an aperture registering with the aperture in said first electrode, a third electrode provided with surfaces intersecting each other and lying parallel to the surfaces of said first electrode and having an aperture registering with the aperture in said first electrode, and a fourth electrode having a surface defined by a hyperbola, the intersecting surfaces extended of said third electrode forming the asymptotes for said last hyperbola, said fourth electrode having an aperture registering with the aperture in said third electrode and cathodes aligned with said apertures for supplying oppositely directed streams of electrons through the apertures in said resonator and between the surfaces of the second and fourth electrodes.

10. An electron discharge device including a resonator the transverse section of the walls of which defines a pair of oppositely disposed sectors, the tips of which are adjacent and having oppositely disposed apertures in the Walls thereof at said tips through which an electron stream can be directed to excite said resonator, an electrode positioned on each side of said resonator, the surfaces of which are defined by hyperbolas, the walls extended of said resonator forming the asymptotes of said hyperbolas, and means registering with said aperture for directing an electron stream through the apertures in said resonator and between the surfaces of the electrodes.

11. An electron discharge device including a resonator the transverse section of the walls of which defines a pair of oppositely disposed sectors, the tips of which are adjacent and having oppositely disposed apertures in the walls thereof at said tips through which an electron stream can be directed to excite said resonator, an electrode positioned on each side of said resonator, the surfaces of which are defined by hyperbolas, the walls extended of said resonator forming the asymptotes of said hyperbolas, one of said elec trodes having an aperture oppositely disposed to the apertures in said resonator, and a cathode lying in the aperture of said one electrode for ro viding an electron stream through the apertures in said resonator toward the surface of the other electrode.

12. An electron discharge device including a resonator the transverse section of the walls of which defines a pair of oppositely disposed sectors, the tips of which are adjacent and having oppositely disposed apertures in the walls thereof at said tips through which an electron stream can be directed to excite said resonator, an electrode positioned on each side of said resonator, the surfaces of which are defined by hyperbolas, the walls extended of said resonator forming the asymptotes of said hyperbolas, one of said electrodes having an aperture oppositely disposed to the apertures in said resonator, and a cathode positioned on the side of said one electrode opposite said resonator and registering with the aperture of said one electrode for providing an electron stream through the apertures in said resonator toward the surface of the other electrode, and a cathode shield surrounding the cathode.

13. An electron discharge device including a resonator, the transverse section of the walls of which defines a pair of oppositely disposed sectors, the tops of which are adjacent and having oppositely disposed apertures in the walls thereof at the tips through which an electron stream can be directed to excite said resonator, an electrode positioned on each side of said resonator, the surfaces of which are each defined by hyperbolas, the walls extended of said resonator forming the asymptotes of said hyperbolas, one of said electrodes having an aperture oppositely disposed to the apertures in said resonator, and a cathode positioned on the other side of the electrode from said resonator and registering with the aperture in said electrode, said electrode and said cathode having independent leads and being adapted to have an alternating voltage applied therebetween during operation of said devices for modulating the stream of electrons directed through the apertures in said resonator.

14. An electron discharge device including an elongated resontator, the transverse section of the walls of which defines oppositely disposed sectors of a circle, said resonator having oppositely disposed apertures in the wall thereof at the tips of said sectors and providing oppositely disposed gaps lying in a plane transverse to the plane passing through said apertures, said gaps communicating with the interior of said resonator, elongated electrodes positioned on each side of said resonator, the transverse section of the surfaces of which are each defined by hyperbolas, the walls extended of said resonator forming the asymptotes of said hyperbolas, one of said electrodes having an aperture oppositely disposed to the aperture in said resonator and an elongated cathode aligned with said apertures for providing an electron stream passing from the aperture in said one electrode through the apertures in said resonator toward the surface of said other electrode.

15. An electron discharge device including an elongated resonator, the transerse section of the walls of which defines oppositely disposed sectors of a circle, said resonator having oppositely disposed apertures in the wall thereof at the tips of said sectors and providing oppositely disposed gaps lying in a plane transverse to the plane passing through said apertures, said gaps communicating with the interior of said resonator, elongated electrodes positioned on each side of said resonator, the transverse section of the surfaces of which are each defined by hyperbolas, the walls extended of said resonator forming the asymptotes of said hyperbolas, cathode means aligned with said apertures for providing an electron stream passing through the apertures in said resonator and between the surfaces of said electrodes, the ends of said sector shaped portions of the resonator communicating with each other at the ends thereof.

16. An electron discharge device including an elongated resonator, the transverse section of the walls of which defines oppositely disposed sectors of a circle, said resonator having oppositely disposed apertures in the wall thereof at the tips of said sectors and providing oppositely disposed gaps lying in a plane transverse to the plane passing through said apertures, said gaps communicating with the interior of said resonator, elongated electrodes positioned on each side of said resonator, the transverse section of the surfaces of which are each defined by hyperbolas, the walls extended of said resonator forming the asymptotes of said hyperbolas, and an elongated cathode aligned with said apertures for providing an electron stream passing through the apertures in said resonator and between the surfaces of said electrodes, and means extending from the walls of said resonator insulatingly supporting said cathode and said electrodes.

LLOYD P. SMITH. 

